Ecology
Scientific study of interactions among
organisms and between organisms
and their physical environment
Biosphere: All life on earth and parts
of earth in which life exists (land,
water and atmosphere)
Studying Our Living planet
• Science of Ecology
– Study of interactions of living things, their
surroundings or environments
• Ecology and Economics
– Humans live in biosphere and depend on
ecological processes to provide essentials (water
and food) which can be bought and sold.
• Levels of Organization
– Species to biosphere
Levels of Organization
• Species-Similar organisms that can breed and
produce fertile offspring
• Population- group of individuals that belong to
the same species/live in same area
• Community-Different populations that live
together in defined area.
• Ecosystem-organisms, their space and the
physical environment
Levels of Organization continued.
• Biome-Group of ecosystems that share
climates and typical organisms
• Biosphere-Entire planet, all organisms, and
physical environment
Biotic factors
Biological influences of organisms
Eg. Other living organisms, food
Abiotic factors
Physical components of an ecosystem
Eg. Sunlight, humidity, wind or water
currents.
Ecological Methods
• Observation-where live? How many live here?
How animals protect young?
• Experiment-used to test hypothesis. How do
growing plants react to different variables?
• Modeling-make models-global warming
happens over time. Use mathematical
formulas based on data.
Energy, Producers and Consumers
Organisms and Energy
Energy needed to grow, reproduce and
metabolize
Organisms can not create energy, must
get it from other sources
Primary Producers
• Autotrophs-capture sunlight or chemicals and
convert it into forms that living cells can use.
• Primary Producers-first producers of energyrich compounds that are later used by other
organisms.
• Eg. Plants, Algae and certain bacteria.
Auto = self (Greek)
Trophe = Food or
nourishment (Greek)
Energy from Sun
The best-known and most common
primary producers harness solar
energy through the process of
photosynthesis
Life without Lights
Biologists have discovered thriving
ecosystems around volcanic vents in
total darkness on the deep ocean floor.
Life Without Light
Deep-sea ecosystems depend on primary
producers that harness chemical energy from
inorganic molecules such as hydrogen sulfide.
The use of chemical energy to produce
carbohydrates is called chemosynthesis.
Consumers
Organisms that rely on other
organisms for energy and nutrients
Organisms that must acquire energy from other organisms
by ingesting in some way are known as heterotrophs.
Heterotrophs are also called consumers.
Heter= other
Types of consumers
– Classified by the ways in which they acquire
energy and nutrients.
– Carnivores kill and eat other animals, and
include snakes, dogs, cats, and this giant river
otter.
– Catching and killing prey can be difficult and
requires energy, but meat is rich in nutrients
and energy and is easy to digest.
Consumers Types continued.
• Scavengers, like a king vulture, are animals that
consume the carcasses of other animals that
have been killed by predators or have died of
other causes.
Consumer Types cont.
• Decomposers, such as bacteria and fungi, feed
by chemically breaking down organic matter.
The decay caused by decomposers is part of the
process that produces detritus—small pieces of
dead and decaying plant and animal remains.
Consumer Types cont.
–
Herbivores, such as a military macaw,
obtain energy and nutrients by eating plant leaves,
roots, seeds, or fruits. Common herbivores include
cows, caterpillars, and deer.
Consumer Types cont.
• Omnivores are animals whose diets naturally
include a variety of different foods that usually
include both plants and animals. Humans,
bears, and pigs are omnivores.
Consumer Types cont.
–
Detritivores, like giant earthworms, feed on
detritus (debris) particles, often chewing or
grinding them into smaller pieces. Detritivores
commonly digest decomposers that live on, and in,
detritus particles.
Decomposer
Organisms that breakdown and absorb
nutrients from dead organisms.
Fungi, protozoan's, bacteria
Beyond Consumers
Categorizing consumers is important, but these
simple categories often don’t express the real
complexity of nature.
For example, herbivores that eat different plant
parts often differ greatly in the ways they obtain and
digest their food.
Not one size fits all
In addition, organisms in nature often do not stay
inside the categories we put them in.
For example, some carnivores will scavenge if
they get the chance. Many aquatic animals eat a
mixture of algae, bits of animal carcasses, and
detritus particles.
It is important to expand upon consumer
categories by discussing the way that energy and
nutrients move through ecosystems.
Energy Flow in ecosystems
How does it flow?
Three types of ecological pyramids
Energy Flow
• One-way stream
• Primary producers to various
consumers
Food Chain
Series of steps in which
organisms transfer energy
by eating and being eaten
Feeding relationships
Food Chains
• Vary in length
• Aquatic food chain primary producers are a
mixture of floating algae called phytoplankton
Food Web: network of feeding
interactions
• Network of food chains
• More complex than food chain; still simplified
Vocabulary
Convert means “to change from one form to
another”.
Decomposers convert dead plant matter into a
form of debris called detritus that was eaten by
detritivores
Decomposers break down dead and decaying
matter and release nutrients that can be reused
by primary producers
w/o decomposers, nutrients would be locked
within dead organisms
Describe three food chains
that are part of this food web.
Food Webs and Disturbances
• So complex, often difficult to predict exactly
how they will respond to environmental
changes.
– Oil spill
• Decline in number of bacteria and fungi that break
down detritus?
• How will effect populations of crayfish?
• Populations decline? If decline how will that affect their
predators feeding behaviors?
Zooplankton
Diverse group of small, swimming
animals that feed on marine algae
What would happen to this food chain
if there was a drop in krill?
Trophic Levels
• Steps in food chain
or food web
(feeding levels)
• PRIMARY
PRODUCERS
ALWAYS first tropic
level.
• One organism can
be at different
trophic levels
Ecological
Pyramids:
illustrate relative
amounts of
energy or matter
contained with in
a trophic level in a
given food chain
or food web.
Three Types of Ecological Pyramids
Pyramid of Energy
• Show relative amount of energy available
• No limit to the number of trophic levels or
number of organisms
• Only small portion of energy goes from one
trophic level to the next. ( 1/10 or 10% goes to
next level)
– Expend energy for life processes (growth,
respiration, movement and reproduction)
– Released as heat
a.If there are 1000 units of energy available at the producer level of the energy pyramid,
approximately how many units of energy are available to third-level consumers?
b.What is the original source of energy that flows through the ecosystems? Why must there
be a continuous supply of energy into the ecosystem?
c.Why are there usually fewer organisms in the top of an energy pyramid?
biomass
Amount of living tissue within a given
trophic level
(measured in grams of organic matter
per unit area)
Pyramid of biomass: illustrates the
relative amount of living organic
matter available at each trophic
level in an ecosystem
Pyramids of Numbers: relative number
of individual organisms at each trophic
level in an ecosystem
Exceptions
• Some cases consumers are less massive than
the organisms they feed upon.
• Sometimes pyramid of numbers may be
turned upside down.
Cycles of Matter
THINK ABOUT IT
– A handful of elements combine to form
the building blocks of all known
organisms.
– Organisms cannot manufacture these
elements and do not “use them up,” so
where do essential elements come from?
– How does their availability affect
ecosystems?
Recycling in the Biosphere
– How does matter move through the biosphere
Recycling in the Biosphere
– Unlike the one-way flow of energy, matter is
recycled within and between ecosystems.
– Elements pass from one organism to another
and among parts of the biosphere through
closed loops called biogeochemical cycles,
which are powered by the flow of energy.
Recycling in the Biosphere
– Biogeochemical cycles of matter involve
biological processes, geological processes, and
chemical processes.
– As matter moves through these cycles, it is
never created or destroyed—just changed.
Biological Processes
– Biological processes consist of any and all
activities performed by living organisms.
– These processes include eating, breathing,
“burning” food, and eliminating waste
products.
Geological Processes
– Geological processes include volcanic
eruptions, the formation and breakdown of
rock, and major movements of matter within
and below the surface of the earth.
Chemical and Physical
Processes
– Chemical and physical processes include the
formation of clouds and precipitation, the flow
of running water, and the action of lightning.
Human Activity
– Human activities that affect cycles of matter
on a global scale include the mining and
burning of fossil fuels, the clearing of land for
building and farming, the burning of forests,
and the manufacture and use of fertilizers.
Recycling in the Biosphere
– Biogeochemical cycles of matter pass the
same atoms and molecules around again and
again.
The Water Cycle
– How does water cycle through the biosphere?
The Water Cycle
– How does water cycle through the biosphere?
– Water continuously moves between the
oceans, the atmosphere, and land—sometimes
outside living organisms and sometimes inside
them.
The Water Cycle
– Water molecules typically enter the
atmosphere as water vapor when they
evaporate from the ocean or other bodies of
water.
– Water can also enter the atmosphere by
evaporating from the leaves of plants in the
process of transpiration.
The Water Cycle
– If the air carrying it cools, water vapor
condenses into tiny droplets that form clouds.
– When the droplets become large enough, they
fall to Earth’s surface as precipitation in the form
of rain, snow, sleet, or hail.
The Water Cycle
– On land, some precipitation flows along the
surface in what scientists call runoff, until it
enters a river or stream that carries it to an
ocean or lake.
– Precipitation can also be absorbed into the
soil, and is then called groundwater.
The Water Cycle
– Groundwater can enter plants through their
roots, or flow into rivers, streams, lakes, or
oceans.
– Some groundwater penetrates deeply enough
into the ground to become part of underground
reservoirs.
Nutrient Cycles
– What is the importance of the main nutrient
cycles?
– Every organism needs nutrients to build tissues
and carry out life functions. Like water, nutrients
pass through organisms and the environment
through biogeochemical cycles.
– The three pathways, or cycles, that move carbon,
nitrogen, and phosphorus through the biosphere
are especially critical for life
Nutrient Cycles
– The chemical substances that an organism
needs to sustain life are called nutrients.
– Every organism needs nutrients to build
tissues and carry out life functions.
– Nutrients pass through organisms and the
environment through biogeochemical cycles.
Nutrient Cycles
– Oxygen participates in parts of the carbon,
nitrogen, and phosphorus cucles by combining
with these elements and cycling with them
through parts of their journeys.
– Oxygen gas in the atmosphere is released by
one of the most important of all biological
activities: photosynthesis.
– Oxygen is used in respiration by all multicellular
forms of life, and many single-celled organisms
as well.
The Carbon Cycle
– Carbon is a major component of all organic
compounds, including carbohydrates, lipids,
proteins, and nucleic acids.
The Carbon Cycle
– Carbon dioxide is continually exchanged
through chemical and physical processes
between the atmosphere and oceans.
The Carbon Cycle
– Plants take in carbon dioxide during
photosynthesis and use the carbon to build
carbohydrates.
– Carbohydrates then pass through food webs
to consumers.
The Carbon Cycle
– Organisms release carbon in the form of
carbon dioxide gas by respiration.
The Carbon Cycle
– When organisms die, decomposers break
down the bodies, releasing carbon to the
environment.
The Carbon Cycle
– Geologic forces can turn accumulated
carbon into carbon-containing rocks or fossil
fuels.
The Carbon Cycle
– Carbon dioxide is released into the
atmosphere by volcanic activity or by human
activities, such as the burning of fossil fuels
and the clearing and burning of forests.
The Carbon Cycle
– Important questions remain about the carbon
cycle.
– How much carbon moves through each
pathway?
– How do ecosystems respond to changes in
atmospheric carbon dioxide concentration?
The Nitrogen Cycle
– All organisms require nitrogen to make
amino acids, which are used to build proteins
and nucleic acids, which combine to form
DNA and RNA.
The Nitrogen Cycle
– Nitrogen gas (N2) makes up 78 percent of
Earth’s atmosphere.
The Nitrogen Cycle
– Nitrogen-containing substances such as
ammonia (NH3), nitrate ions (NO3), and nitrite
ions (NO2) are found in soil, in the wastes
produced by many organisms, and in dead
and decaying organic matter.
The Nitrogen Cycle
– Dissolved nitrogen exists in several forms in
the ocean and other large water bodies.
The Nitrogen Cycle
– Although nitrogen gas is the most abundant
form of nitrogen on Earth, only certain types
of bacteria that live in the soil and on the roots
of legumes can use this form directly.
– The bacteria convert nitrogen gas into
ammonia, in a process known as nitrogen
fixation.
The Nitrogen Cycle
– Other soil bacteria convert fixed nitrogen into
nitrates and nitrites that primary producers
can use to make proteins and nucleic acids.
The Nitrogen Cycle
– Consumers eat the producers and reuse
nitrogen to make their own nitrogencontaining compounds.
The Nitrogen Cycle
– Decomposers release nitrogen from waste
and dead organisms as ammonia, nitrates,
and nitrites that producers may take up again.
The Nitrogen Cycle
– Other soil bacteria obtain energy by
converting nitrates into nitrogen gas, which is
released into the atmosphere in a process
called denitrification.
The Nitrogen Cycle
– A small amount of nitrogen gas is converted
to usable forms by lightning in a process
called atmospheric nitrogen fixation.
The Nitrogen Cycle
– Humans add nitrogen to the biosphere
through the manufacture and use of fertilizers.
Excess fertilizer is often carried into surface
water or groundwater by precipitation.
The Phosphorus Cycle
– Phosphorus forms a part of vital molecules
such as DNA and RNA.
– Although phosphorus is of great biological
importance, it is not abundant in the
biosphere.
The Phosphorus Cycle
– Phosphorus in the form of inorganic
phosphate remains mostly on land, in the
form of phosphate rock and soil minerals, and
in the ocean, as dissolved phosphate and
phosphate sediments.
The Phosphorus Cycle
– As rocks and sediments wear down,
phosphate is released.
– Some phosphate stays on land and cycles
between organisms and soil.
The Phosphorus Cycle
– Plants bind phosphate into organic
compounds when they absorb it from soil or
water.
The Phosphorus Cycle
– Organic phosphate moves through the food
web, from producers to consumers, and to the
rest of the ecosystem.
The Phosphorus Cycle
– Other phosphate washes into rivers and
streams, where it dissolves. This phosphate
eventually makes its way to the ocean, where
marine organisms process and incorporate it
into biological compounds.
Nutrient Limitation
– How does nutrient availability relate to the
primary productivity of an ecosystem?
– If ample sunlight and water are available, the
primary productivity of an ecosystem may be
limited by the availability of nutrients.
Nutrient Limitation
– Ecologists are often interested in an
ecosystem’s primary productivity—the rate at
which primary producers create organic
material.
– If an essential nutrient is in short supply,
primary productivity will be limited.
– The nutrient whose supply limits productivity is
called the limiting nutrient.
Nutrient Limitation in Soil
– The growth of crop plants is typically limited by one
or more nutrients that must be taken up by plants
through their roots.
– Most fertilizers contain large amounts of nitrogen,
phosphorus, and potassium, which help plants grow
better in poor soil. Carbon is not included in chemical
fertilizers because plants acquire carbon dioxide from
the atmosphere.
– Micronutrients such as calcium, magnesium, sulfur,
iron, and manganese are necessary in relatively small
amounts, and are sometimes included in specialty
fertilizers.
Nutrient Limitation in Soil
– All nutrient cycles
work together like the
gears shown.
– If any nutrient is in
short supply—if any
wheel “sticks”—the
whole system slows
down or stops
altogether.
Nutrient Limitation in Aquatic
Ecosystems
– Oceans are nutrient-poor compared to many
land areas.
– In the ocean and other saltwater environments,
nitrogen is often the limiting nutrient.
– In streams, lakes, and freshwater environments,
phosphorus is typically the limiting nutrient.
Nutrient Limitation in Aquatic
Ecosystems
– Sometimes an aquatic ecosystem receives a
large input of a limiting nutrient—for example,
runoff from heavily fertilized fields.
Nutrient Limitation in Aquatic
Ecosystems
– The result of this runoff can be an algal bloom—a
dramatic increase in the amount of algae and other
primary producers due to the increase in nutrients.
– If there are not enough consumers to eat the algae,
an algal bloom can cover the water’s surface and
disrupt the functioning of an ecosystem.